A thin display (particularly a large size) has been actively researched and developed as a next generation display panel, but it has not yet come to explosively spread at the present time. The largest cause thereof is a high cost in addition to a quality thereof such as a resolution on a picture plane, and particularly the price for general users has to be lowered to a large extent.
One of causes for expensiveness of the display described above resides in that a display panel, particularly a back face base panel is expensive, and the reason therefor is that a barrier rib has to be precisely worked.
The barrier rib described above is produced by shaving out a rib by means of a sand blast or piling up a rib by a printing method. A rib material comprises particles of glass and ceramic and a paste (organic substance: about 20% by weight) of an organic compound and are as very expensive as several ten thousand yen/kg. In a sand blast method, this is fixed on a back face glass base, and then a rib is shaved out. In this case, about 70% by weight is finally shaved off to become dusts (impossible to recycle), and the efficiency is very bad. Further, the sand blast has a low precision and takes time. On the other hand, waste of rib materials is reduced in the printing method, but printing is repeated to produce a rib, so that longer time than in the sand blast method is required for molding the rib, and the productivity is very inferior. Further, deviation is caused in piling up, and therefore the precision is not necessarily good.
The back face base can not help becoming expensive because of such reasons. Accordingly, the respective makers concentrate their efforts on research and development of a method by which the back face base can be manufactured at a low cost, and a hot press-embossing method has been developed as the simple production process by a part of them. However, the production speed has resultingly been almost the same as that of the sand blast because a rib is cured by hot curing, so that curing time therefor is required, and pressing is required during curing, so that the efficiency is inferior.
On the other hand, it has so far been investigated in various fields to apply an energy ray-curing resin having a characteristic of energy ray curing represented by UV curing to a barrier rib. However, a shortage in a capacity of energy ray curing is given as a factor which inhibits application thereof.
An energy ray-curing resin represented by a UV-curing resin is characterized by that only a part irradiated with a fixed amount or more of an energy ray is cured, and an energy ray represented by UV is characterized by that it is attenuated in the course of transmitting through the resin, so that a phenomenon of energy ray-curing is characterized by that it is influenced to a large extent by a curing capacity of the resin itself and an intensity, an irradiation time and an attenuation characteristic of the energy ray.
Methods which have so far been carried out in order to elevate an energy ray-curing capacity include an elevation in a performance of a photoinitiator, a rise in an intensity of an energy ray irradiated, an extension of an irradiating time and a change in the kind of energy rays.
However, when employing the methods described above, such problems that time and cost are taken for developing an initiator and a resin composition is expensive have been involved in the side of the resin composition. Also, problems such as an expansion in the apparatuses, an increase in consumed energy, a rise in the running cost, a reduction in the productivity, a specialization in a ray source, high costs of the apparatuses and the facilities and a reduction in the safety have been involved in the side of the energy ray irradiation apparatuses and the facilities. This has presented the state that it is resultingly difficult to use and apply the above methods themselves if the problems such as a loss of the advantages of energy ray-curing and an increase in the total cost are not solved.
Conventional high curability energy ray-curing resins represented by a high UV-curing resin have so far been dependent on development of novel photopolymerizable initiators which are effective for energy ray-curing or, though examples thereof are smaller than the above, development of novel photopolymerizable oligomers, and the situation has been that it is not necessarily possible to readily obtain the compositions suited to uses. Further, UV-heat combined curing type resins are characterized by that they have broader curing conditions. On the other hand, the preceding problems involved in the high curability energy ray-curing resins remain as they are. Further, requirement for a heating process leads to requirement for a heating apparatus and facilities, so that the advantages of energy ray-curing have been damaged as well in terms of an apparatus and facilities.